fuel mpg help

[frankenstien]

i had a tangent on another post i had about my less that great mpg, one guy commented that theres something wrong lol

so i have a 2006 yukon denali xl, it cam from california to alaska with 71k on it, i had it shipped here, it currently has 78k on it and has new tires(less than 7k) new plugs and wires, borg warner wires and ac delco plugs, not iridum but a platnium plug, cant remember the name, ams oil in the front and rear diff, mobil 1 delvac in the t case, eliminated air ride, tires are 265/70/17 cooper discoverer at3's

it has never gotten real great milage, gets about 10.5-11 mpg average, best was 13.3,

ay ideas or suggestions?

 

[Walkercraig01]

My first thought was temp change.. but that's awful

 

[frankenstien]

Its summer here, we had some 80 degree days, its headed towards winter now, won't be til October til snow falls

Engine seems to run good, no issues with power, maybe it has a tune in it? There were some things that made me think the person before me wasn't the brightest crayon

 

[scoobyxj]

Not awful at all. I don't think. My 04 5.3ltr 4x4 Tahoe was getting 11.9 as an average until I put a programmer on it, and it jumped to 14.9.

 

[Walkercraig01]

I get 17 18 on the highway my avg is 15.4

 

[ccapehartusarmyINF.(ret)]

i was gonna ask if you were running e85 because thats e85 mileage but i noticed yer in fairbanks alaska and i know there isnt any e85 stations in alaska
whats yer average altitude and temp in yer area summer and winter

 

[frankenstien]

altitude is about 800 i think? averags 70s summer, was a bit hotter this summer, got up to 80/90

yeah i dont know, i didnt think the 6.0 was that bad, and it beign awd doesnt help, but it seems like something is up

---------- Post added at 09:39 PM ---------- Previous post was at 09:36 PM ----------

also may be transmission related, found a hole nexto the filter seal hole, i have a post somewhere about it

http://www.tahoeyukonforum.com/forum/showthread.php?t=74483

 

[frankenstien]

Got 12 the other day in town, hot damn.

 

[ccapehartusarmyINF.(ret)]

altitude is about 800 i think? averags 70s summer, was a bit hotter this summer, got up to 80/90

yeah i dont know, i didnt think the 6.0 was that bad, and it beign awd doesnt help, but it seems like something is up

---------- Post added at 09:39 PM ---------- Previous post was at 09:36 PM ----------

also may be transmission related, found a hole nexto the filter seal hole, i have a post somewhere about it

http://www.tahoeyukonforum.com/forum/showthread.php?t=74483

holy crap dude it gets that warm in the summer ive been to ft wainright in the dead of winter and it was dark all the time and so freakin cold my piss actually started to freeze and the nights were very long but those northern lights were something else
im sure it was well below 0

the only thing i can think of that mite be climate related is like in extremely cold climates when you start the vehicle the PCM runs in open loop wich is a rich mixture till the engine reaches a certain temp but if its really cold and it cant warm up enough itll keep running in open loop

 

[frankenstien]

, but its doing this in the summer, the winter fuel mpg really isn't fair to measure as it is cold as hell, so it stays running most of the day when were out.and about, at store etc. And the auto start before you leave somewhere.

As it.is now its start up and go